92 
LYMNAIDZ OF NORTH AMERICA. wo 
fi 
SHELL: Small, rather solid, varying from ovate to elongate-ovate ; 
color light yellowish or brownish; surface shining, with heavy growth 
lines crossed by very fine, almost microscopic spiral impressed lines ; 
nuclear whorls as in cubensis; whorls 5-5%, well rounded, the spire 
whorls inclining to become shouldered, the body whorl very convex; 
spire attenuated, broadly conical, about as long as the aperture; sutures 
well impressed ; aperture ovate or roundly ovate, its axis nearly parallel 
with that of the shell; outer lip thin, with an internal varix edged with 
violet; inner lip reflected and turned back over the umbilical region, 
forming a narrow, somewhat elevated expansion; parietal wall with 
marked callus; umbilical chink large and conspicuous; axis of the 
whorls as in cubensis. 
Length. Breadth. Aperture length. Breadth. 
7.00 4.50 aes . mill. Adams 
6.75 4.00 3.50 aly mee Rhode Island. 
6.00 3.40 3.00 1290) e = 
ets 4.00 3e15 200) a Maine. 
7.00 3.00 3.50: 2.00) * 
7.00 4.00 3.50 2.000 = a 
6.00 3.50 2.75 125 Grifiithiana 
Types: Umbilicata, Amherst College. Cotypes: Phil. Acad. 
Sci. (eight specimens, No. 58507) ; Smithsonian Institution, No. 28158 
(Binney’s No. 8249); Museum of Middlebury College, Vermont; 
griffithiana, Smithsonian Institution, two specimens, No. 119467. 
Type Locatitry: New Bedford, Massachusetts, for umbilicata; 
Charlotte Lake, Columbia County, New York, for griffithiana. 
ANIMAL: Not differing from the other small Lymnzas. 
Jaw (plate VI, fig H): Wide and low, much arched with a 
narrow, acute median projection on the ventral margin. 
RApDULA (plate VIII, figs. A, B): Formula: 1542444144431 35 
(22-1-22) ; central tooth with rather wide cusp; lateral teeth tricuspid, 
the mesecone very long and wide, the entocone and ectocone smaller ; 
the fourth and fifth laterals become elongated, the entocone moves 
toward the distal end and becomes larger and the mesocone becomes 
smaller; the true marginals begin at the seventh tooth and consist of 
a long and narrow, bifid entocone, a larger mesocone and a smaller 
ectocone; one or two very small serrations appear on the reflection 
above the ectocone; the outer marginals become claw-like with from 
three to five serrations at the distal end and several smaller serrations 
on the outer margin. There are about 90 rows of teeth. The teeth 
are quite uniform, little variation being seen in several membranes 
examined. In one membrane the seventh tooth (transition) was dis- 

